4over4 might be a bit more popular than Endicia. We know about 1 link to it since March 2021 and only 1 link to Endicia. We are tracking product recommendations and mentions on various public social media platforms and blogs. They can help you identify which product is more popular and what people think of it.
I have purchased hundreds of dollars of stamps from a one "JC" on Facebook. They are not regular stamps but printed ones from stamps.com and endicia.com with unique designs and barcodes. Many of the sales this user does are for stamps in amounts of $1, $2.21, $4.08. $6.67, $10.75 $11, $27, & $32 (along with regular "Forever" stamps). I have used all of these on letters, boxes, etc and shipping domestic and foreign... Source: almost 2 years ago
I've looked myself, let me know if you find them. I think they were a custom run of cards. On the back it has "Free by 4over4.com", but I think that was just a promo or something at the time. Source: almost 3 years ago
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